Thermal characterization of materials, especially civil engineering materials, in the way of non-destructive methods, are more and more widespread. In this article, we show an original point of view to describe the used method, the thermal waves, to obtain the thermal impedance of the studied system, using a specific sensor - a fluxmeter. The identification technique, based on a frequential approach, is optimized by applying a random input to the system. This kind of random heating is shown to provide a frequency range where the thermal effusivity is able to be identified and not correlated to another parameter. The strength of the method is also the determination of the contact resistance of the system, that allows to validate the identification process. Experimental results obtained from a sample with well-known thermal properties (polyvinyl chloride) are used to validate the proposed method.

This work investigates the thermal properties of polyvinyl chloride and asbestos ceiling sheet. We have studied the thermal properties of these materials in terms of the thermal conductivity (TC), thermal resistivity (TR), thermal diffusivity, thermalabsorptivity, and specific heat capacity...

The article evaluates the use of thermal non-destructive testing, pulsed thermography(PT) on certain aircraft applications. The experiment provided effective results to assess surface or near-surface defects on aerospace materials. The objective was to locate anchoring points of aircrafts...

Corrosion of steel strands in prestressed concrete (PC) bridges may lead to substantial damage or collapse well before the end of the design life. Acoustic Emission (AE) is a suitable nondestructive technique to detect and locate corrosion in reinforced and prestressed concrete, which is key to...

Most commercial ultrasonic NDE equipment employs a voltage spike to stimulate a piezoelectric transducer. To protect the signal processing unit from damage from this spike, a voltage limiter or â€œdiode clampâ€ is included in the pulser-receiver, and limits the voltage reaching the...

This article deals with thermal properties of selected kinds of timber. Wood, generally, is one of often used natural materials in building structures. For our research, woods were selected according to frequency of utilization in civil engineering branch. Four different timbers were chosen, and...

This paper has the final goal to develop an analytical method that permits experimental design for active non-destructive infrared testing. This consists in the predetermination of the required frequency of the input thermal signal given the depth of interest for the investigation of possible...

Carbon nanotubes (CNTs) are considered the most promising candidates to replace Cu and Al in a large number of electrical, mechanical and thermal applications. Although most CNT industrial applications require macro and micro size CNT fiber assemblies, several techniques to make conducting CNT...

Nondestructive testing (NDT) for flaws in materials and structures has undergone an evolutionary change over the past 50 years. In the U.S. it has moved from a testing strategy (NDT) with a zero defects requirement to a test and evaluate technology (NDE) based upon damage tolerant design...

Composite structures consisting of an epoxy resin matrix filled with a porous perlite containing a finely dispersed polyvinyl chloride are investigated. Models of the composites are analyzed in which the formation of a transition layer between the filler particles and the matrix may arise as a...